I. Field
The present invention relates generally to circuits, and more specifically to injection locked (IL) dividers for frequency synthesis. IL dividers are also commonly referred to as IL frequency dividers (ILFDs), IL oscillators, etc.
II. Background
A wireless device (e.g., a cellular phone or a smartphone) may transmit and receive data for two-way communication with a wireless communication system. The wireless device may include a transmitter for data transmission and a receiver for data reception. For data transmission, the transmitter may modulate a transmit local oscillator (LO) signal with data to obtain a modulated radio frequency (RF) signal, amplify the modulated RF signal to obtain an output RF signal having the desired output power level, and transmit the output RF signal via an antenna to a base station. For data reception, the receiver may obtain a received RF signal via the antenna, amplify and downconvert the received RF signal with a receive LO signal, and process the downconverted signal to recover data sent by the base station.
The wireless device may include one or more phase-locked loops (PLLs) to generate one or more oscillator signals at one or more desired frequencies. The oscillator signal(s) may be used to generate the transmit LO signal for the transmitter and the receive LO signal for the receiver. The PLL(s) may be required to generate the oscillator signal(s) with good phase noise performance. The PLL(s) should also consume as little battery power as possible in order to extend battery life and prolong standby time and talk time of the wireless device.